Printing with ink sometimes requires application of a liquid spray to an ink image to complete the printing or finishing process. For example, in dip transfer printing, a pattern is printed in solvent based ink on a water soluble film such as polyvinyl acetate. The printed film is then placed on the surface of water in a dipping tank with the printed side up and the soluble film side down. The water dissolves the water soluble film while a solvent activator, such as xylene, is sprayed from the sprayer over the printed solvent based ink image. The printed image then becomes fluid and the object to be printed is dipped into the water in the dipping tank through the floating printed ink image. The ink adheres to the object immediately and the object is removed from the tank and dried. The result is a seamless print on the object.
Applying the liquid solvent activator uniformly to the ink image at an appropriate rate produces a high quality transfer printing. Too much activator blurs the ink images and, without enough activator, the ink image will not adhere to the surface of the object being printed.
Liquid solvent activator has been applied to ink images in dip transfer printing with hand held sprayers and with spray nozzles carried on a bar which extends across the top of a dipping tank. The bar carrying the spray nozzles travels back and forth along the length of the bath. The bar is carried on wheels at each end of the bar. The wheels ride along both sides of the bath on tracks. The wheels of such an applicator sometimes bind and slow or even stop the applicator. As a result, the applicator applies liquid activator nonuniformly and the resulting coating is nonuniform. Hand held sprayers apply liquid activator only if the operator is very skilled. There are similar problems with applying other liquid coatings such as varnish or lacquer top coatings.
Accordingly, there is a need for a liquid coating applicator that applies liquid uniformly and there is a particular need for a printing system for an activator applicator that applies activator uniformly to an ink image.